This is a really great question. The fun thing about population genetics, (as opposed to the more experimental fields in biology) is that we can actually enume

This is a really great question. The fun thing about population genetics, (as opposed to the more experimental fields in biology) is that we can actually enumerate the forces (mutation, selection and random drift) that are acting on our subject of inquiry (an antibiotic resistance gene in a population of bacteria). The phrase you'll want to google is "time to fixation", and there's some really elegant work on the subject (check out Kimura's 1962 paper "On the Probability of Fixation of Mutant Genes in a Population" http://www.physics.rutgers.edu/~morozov/677_f2017/Physics_677_2017_files/Kimura_Genetics1962_classic.pdf http://www.physics.rutgers.edu/~morozov/677_f2017/Physics_67... ) . All of the theoretical results tend to be in generation time, not chronological time, but you get the idea